Method of hardening iron



' Patented Nov. 18, 1924.

-DONALD MOCORMICK SCOTT, OF ROCHESTER, NEW YORK, ASSIGNOR TO THE '1.

SYMINGTON COMPANY, OF NEW YORK,

N. Y., A CORPORATION OF DELAWARE.

METHOD OF HARDENING IRO'N.

'NoDrawingn To all whom it may concern:

Be it known that I, DONALD M. Soon, a

I citizen of the United States, residing at Rochester, in the county of Monroe and 6 State of New York, have invented certain new and useful Improvements in Methods of Hardening Iron; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will loenable others skilled in the art to which it appertains to make and use the same.

The invention relates'to a method of hardening metal, and more particularly to a method of forming a hard wear-resisting 1 surface or section on a malleable iron casting without the demalleabilization of the portion of the casting surrounding or adjacent to the hard surface or section. p

The principal object of my inventiomgenerally considered, isto provide a method of surface hardening malleable iron so as to adapt the same to resist wear, the said meta to pass into solution and at the same time to maintain the opposite surface or section at a sufficiently reduced temperature to prevent any change in the character or chemical com- 7 position of the metal.

Another feature of the invention consists to a clean surface of a malleable casting a eatin element and applying to the opposite sur ace of said casting a cooling medium, the heating element being adapted to cause the free graphitic carbon of the adjacent surface to go into solution and -the cooling medium being adapted to prevent a rise in temperature of said opposite surface so that no change in composition shall take place therein during the heating operation.

Other features of the method will appear in connection with the more detailed descri tion of the invention. k j I alleable iron, ow'ing'to its strength and ductility, is largely used in railway car castings, and it is peculiarly adapted, owing to those characteristics, for use in the production of journal boxes for railway cars.- It

is, however, a relatively soft metaland is consequently sIlbjected torapid wear when Application filed September 4, 1 923. Serial No. 660,942. i

used in connection with a pedestal type of truck where there is a constant relative movement between the journal box and the pedestal. Various means and expedients have been employed to obviate or overcome the detrimental wear upon the journal box .in a pedestal type truck, such as the use of" liners and casting inserts in the box, 1ubrication, etc. These expedients have not proved entirely satisfactory in service owing to numerous inherent defects, such as the difficulty of properly renewing wear plates under service conditions, the-In-ixtureof grit and dust with the lubricant aggravating.

rather than remedying the Wear upon pedestal Ways; and it is the broad purpose of my invention to overcome and eliminate these defects and deficiencies.

The composition of malleable iron is such that it has heretofore been considered impossible to surface harden the same without at the same time demalleableizing the adjacent metal. In other words, any attempt to surface harden malleable iron has resultedin changing the malleable iron adjacent said surface to hard'cast iron with the consequent result that the secti'on loses its ductility and becomes exceedingly brittle;

The process is primarily intended for use in connection with blackheart malleable iron and in carr in out m rocess I first remove the decarbonized surface, caused by the anneal, by machining this surface, or I employ, during the annealing some carbonizing material, such for instance as charcoal, bone dustfor the like, so as to prevent decarbonization. during the anneal. I prefer, however, to use the machining process, since by achining, that is, planing, grinding or the like, I am enabled toproduce a Smooth and uniform surface.

The next step in the process is to apply to the surface or a portion thereof to be hardened, heat sufficient to cause the graphitic carbon to change from a free state and to, go back into solution so as toform. a

compound with the iron. In order to prevent the demalleableization of the entire The temperature may be obtained upon the surface treated in a number of ways,

5 such for instance as an electric are, electric resistance, or by subjecting the same to the flame of an acetylene torch in which the oxygen and acetylene are so combined as to afford a neutral flame, and it is preferable to when utilizing this method to treat small sections rather than a large area of surface.

ll claim l. The method of hardening malleable iron which consists in eliminating the dele carbonized :surface from a section thereof, applying to said surface a heating element of scient temperature todrive the graphitic carbon into solution and at the same 7 time to apply to the opposite face or surface at of the section treated a cooling medium to prevent the demalleabilization of the entire section. o 2. Flhe method of hardening malleable iron which consists in removing from the 2 surface to be treated the decarbonized material, applying to said surface a heating medium of suficient temperature to drive the graphitic carbon into solution and at the same time subjecting-the opposite surface of the section to be treated to a cooling medium to provide aradical drop in temperature from the surface treated to the opposite surface of the said section. v

3. The method of hardening 'malleable narrate? iron which consists in forming on the surface of the section to be treated a surface free from decarbonized material, subjecting said surface or a portion thereof to a heat suflicient to drive the graphitic carbon into solution and at the same time maintaining a radical drop in temperature between the surface treated and the opposite surface of said Section 4. The method of hardening malleable iron which consists in machining the surface of a section to be hardened so as to remove therefrom the decarbonized material subjecting said surface or a portion thereof to the flame of an oxy-acetylene torch for a sufiicient period to drive the g'raphitie carbon into solution and at the same time subjecting the opposite surface of the section being treated to a cooling medium so as to provide a radical drop in temperature through the section.

5. The method of hardening malleable iron which consists in machining the surface of'a section to be treated so as to remove til) therefrom the decarbonized material, subjectingsaid surface to the neutral flame of an oxy-acetylene torch and at the same time subjecting the opposite surface of said section to a cooling fluid so .as to provide a radical drop in temperature through the" heated surface to the cooled surface of said section.

lln testimony whereof I afiix my si mature.

DONALD MoGQiRMllCK STE. 

